Piercing ram arrangement for an extrusion press



Aug. 1959 M. ARENZ 2,901,104

PIERCING RAM ARRANGEMENT FOR AN EXTRUSION PRESS Filed April 11, 1955 I Ml l i I I i i 3' I I 3 I 1 'H l i: :l 1{

"1 7 an ii "I. 7 4-- N ii'l 47 INVE/VIUP: (4 od Mk6 H enz PIERCING RAMARRANGEMENT FOR AN EXTRUSION PRESS Application April 11, 1955, SerialNo. 500,504 7 In Germany November 26, 1949 Public Law 619, August 23,1954 Patent expires November 26, 1969 1 Claim. (Cl. 201-3) The presentinvention relates to extrusion presses.

More particularly, the present invention relates to an extrusion pressfor extruding tubular articles.

As is well known, such tubular articles ar extruded from a solid billetwhich is first pierced by a piercing ram of the extrusion press. Afterthe billet is pierced, the piercing ram remains in its positionextending through the billet, and then the hydraulic ram compresses thebillet to force it through the extrusion die while the piercing ram actsas a mandrel along which the work material moves. The tension to whichsuch a piercing ram is subject by the extruded material rubbing againstthe same sometimes becomes so great that the result is a failure of thepiercing ram with consequent shutting down of the apparatus and areplacement of the broken piercing ram.

The piercing ram is weakened considerably during the extrusion processby the great heat generated by extrusion of the billet, and althoughbreakdown of the piercing ram has been reduced by making these piercingrams of special alloys, nevertheless complete protection from pullingthe piercing ram apart has not beeen obtained up to the present timewith conventional presses.

One of the objects of the present invention is to overcome the abovedrawbacks by providing a piercing ram with a means which will enable itto shift axially together with the extruded material whenever the latterexerts on the piercing ram a pulling force above a given value.

A further object of the present invention is to provide a means whichyieldably resists movement of the piercing ram together with theextruded material.

Another object of the present invention is to provide a means foradjusting the force at which a piercing ram will shift together with theextruded material.

With the above objects in view, the present invention mainly consists ofan extrusion press which includes a piercing ram and a moving meansoperatively connected to the piercing ram for moving the same in apiercing 55 direction which causes th piercing ram to pierce a billet.

A connecting means connects the piercing ram to the moving means foryieldable movement in the piercing direction independently of the movingmeans when the work material exerts on the piercing ram a force above 0a given value.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claim. Theinvention itself, however, both as to its construction and its method ofoperation, to- 5 gether with additional objects and advantages thereof,will be best understood from the following description of a specificembodiment when read in connection with the accompanying drawing.

The drawing shows a partly diagrammatic, fragmentary, 70 elevationalview of a press constructed in accordance with the present invention.

nited States Patent 0 In the interest of conciseness the drawing showsonly enough structure to afiord a complete understanding of theinvention. Many extrusion press parts not shown in the drawing arepurely conventional and well known to those skilled in the art.

Referring to the drawing a vertical extrusion press is diagrammaticallyillustrated therein. This press includes a hydraulic extruding ram 1fixed to a piston 2 which is slidable within a cylinder 3 supplied witha hydraulic fluid under pressure in any known way. Piston rod 2' of thepiston 2 extends slidably through the top of cylinder 3. The cylinder 3is carried by a part 3' of the press. The palts 1 and 2 are axiallybored to accommodate, in a known way, a piercing ram 4, 5 come posed ofthe elongated piercing element 4 which is fixed at its top end to theremainder of the piercing ram 5. The piercing ram 4, 5 is axiallyslidable through and with respect to the parts 1 and 2. The piercing rampart 5 has a top free end portion 5' of reduced diameter which extendswith a slight clearance through a bore of a cross bar 7. The cross bar 7bears against a shoulder 8 located between end portion 5' and theremainder of the piercing ram part 5. The cross bar 7 is fixed to a pairof piston rods respectively connected to pistons which are slidable inthe cylinders 6, also carried by the frame part 3, and to which fluidunder pressure is supplied in any known way for moving cross bar 7together with the piercing ram downwardly independently of the piston 2through which part 5 slidably extends. A coil spring 9 is coiled aboutthe end portion 5, bears at one end against the cross bar 7, and bearsat its opposite end against an annular member 15 which keeps the spring9 compressed. 'Ihe annular member 15 may be in the form of a nutthreaded on to the end portion 5' to compress spring 9 to a desireddegree in accordance with the particular material being extruded, forexample.

Th drawing shows diagrammatically the container 16 in which the billet17 is located, this billet resting on extrusion die 18. In operation,the parts shown above container 16 are lowered until ram 1 engages thebillet 17, then hydraulic fluid is applied to the cylinders 6 to moveonly the piercing ram downwardly through the billet 17 to the position 4shown in dotted lines. Thereafter, the piercing ram 4, 5 is maintainedin this position and hydraulic fluid is supplied to cylinder 3 to lowerthe hydraulic ram 1 and extrude material through the die 18. Should thismaterial pull downwardly on the piercing ram with a force whichotherwise would break the ram, the entire piercing ram will shiftdownwardly with respect to cross bar 7 compressing the spring 9 which isset to yield only when a force which might break the piercing ram isapplied thereto. The piercing ram might then shift down to the positionindicated at 4" which is sufficient to avoid the danger of breaking thepiercing ram, and then the spring 9 expands to return the piercing ramto its operating position while the extrusion process continues.

The invention obviously is applicable to horizontal as well as verticalpresses, and the invention also is applicable to presses where thepiercing ram is mounted diiferently from the embodiment shown in thedrawing.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofextrusion presses differing from the types described above.

While the invention has been illustrated and described as embodied inpiercing ram arrangement for extrusion presses, it is not intended to belimited to the details shown, since various modifications and structuralchanges may be made without departing in any way from the spirit of theinvention.

Without further analysis, the foregoing will 'so fully reveal the gistof th present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpointoffipriorart, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations shouldand are intended'to becomprehended within the meaning and range of equivalence of thefollowing claim.

What is claimed as new and desired to be secured by Letters Patent is:

In an extrusion press, in combination, an elongated piercing ram havingan elongated free end portion of a diameter smaller than the nextportion of said ram and joined thereto by a shoulder; a cross bar formedwith an opening through which said end portion of said ram passes withslight clearance, said cross bar engaging said shoulder; moving meansfor moving said cross bar toward the end of said ram distant from saidfree end por- References Cited in the file of this patent UNITED STATESPATENTS 349,015 Thompson Sept; 14, 1886 861,194+v Schwieger, July 23,1907 1,150,394 Schlenstedt Aug. 17, 1915 1,664,990 Oehmig et a1 Apr. 3,1928 FOREIGN PATENTS 233,891 Germany Apr. 26, 1911 822,988 Germany Nov.29, 1951

